The Discovery-Dob-Users Mailing List

Frequently Asked Questions

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Section 2: Telescope Selection

2.1) Before You Do Anything Else...
2.2) What is a Dobsonian telescope, or Dob?
2.3) Why should I choose Discovery?
2.4) What are the differences between DHQ and Premium DHQ?
2.5) Is the Premium DHQ worth the extra money, over the DHQ?
2.6) Can I customize my order?
2.7) Can I special order a hybrid telescope?
2.8) What's the deal with Discovery telescope lead times?
2.9) Where can I read some reviews about Discovery telescopes?

2.1) Before You Do Anything Else...

If you are considering your first telescope, stop!  Before you do anything else...

2.2) What is a Dobsonian telescope, or Dob?

A Dobsonian telescope might be defined as follows (adapted from the definition found in the sci.astro.amateur FAQ):  Named for John Dobson of The San Francisco Sidewalk Astronomers, this is an implementation of a Newtonian reflector telescope which allows for very large apertures at very affordable prices. The trade-off is that they are mounted on altitude-azimuth mounts, instead of equatorial mounts, which makes them essentially useless for astrophotography, but an inexpensive alternative if you only plan to do visual work. These are light buckets.

[Rich Dodson] By spending additional money (several hundred to a thousand dollars, or more) for an equatorial platform, it is possible to track planets and deep-sky objects for up to about an hour with a Dob.  Admittedly, the concept of an "inexpensive alternative" begins to break down a bit when you start adding more stuff, but a limited amount of astrophography is possible with these gizmos.

2.3) Why should I choose Discovery?

There are many possible answers to this.  Here are a couple that leap to mind:

(1) Price-to-performance ratio.  Discovery scopes are a very good value.  People who want the ultimate in performance have many choices: Starmaster, Obsession, and a world of fine apochromatic refractors. There are also a ton of bargain bag telescopes, which cost a couple hundred bucks and promise the heavens.  But there are only a few manufacturers who walk the middle ground, offering a compromise on performance at great prices.  Buying from these manufacturers (including Discovery) is an exercise in knowing in what areas you're willing to compromise. 

The main respectable competition for the Discovery DHQ line comes from Guan Sheng (Dobs sold in the US through Hardin Optical, Celestron dealers, and others) and Synta (Dobs sold in the US as the Orion Skyquest XT series and available elsewhere under the Skywatcher brand). Guan Sheng in particular has gotten a reputation for being able to mass-produce good mirrors. These telescopes have steel tubes and tensioning springs on their altitude bearings. There are a couple of other minor differences, and different sellers may offer a variety of standard accessories. At times, these imported Dobs may be significantly cheaper than the DHQ's, so they're certainly worth consideration. Note: As of the current update of this FAQ, the DHQ line has been discontinued. Discovery has also become a Celestron dealer. DHQ scopes still show up on the used market sometimes.--Wes Stone

The Discovery PDHQ series has less competition in the price range. Currently, the largest Dobs produced by Guan Sheng and Synta are 12"; the PDHQ line features slower 8" and 10" scopes, with f/5 and faster scopes starting at 12.5". The Meade Starfinder scopes may still be available in 12.5" and 16" sizes, and while the optics tend to be good the general consensus is that the quality of construction is rather poor. Other "premium" solid-tube Dobs are scarce. On the other hand, there are too many truss-based scopes to mention. --Wes Stone

(2) Great, no-compromise optics.  The fact of the matter is that Discovery spends a lot of its money on making sure the mirrors are of very good quality, while keeping the price reasonable by wrapping them in decent to good quality tubes or trusses, and bases.  The optics are generally considered to be not quite as astonishingly awesome as those produced by craftsmen like Zambuto and companies like Pegasus, but they're still great in general. (All manufacturers occasionally let a substandard mirror slip through. --Wes Stone)

2.4) What are the differences between DHQ and Premium DHQ?

The DHQ line, consisting of less-expensive Dobs in the 6-10" class (with occasional limited offerings of larger sizes) has been discontinued. I'll leave this information in the FAQ to aid prospective buyers of used scopes. --Wes Stone.

The PDHQ line is offered in 8, 10, 12.5, 15, 17.5 and 20-inch varieties.  There are many smaller differences, but the big items you get with the Premiums include:

2.5) Is the Premium DHQ worth the extra money, over the DHQ?

The 8, 10, and 12.5-inch PDHQ scopes have competition from the DHQ line. Through the eyepiece, there is not likely to be much difference. To stereotype, the DHQ purchaser wants a cheap, workable scope. The PDHQ purchaser is willing to spend a bit of extra money for a scope that's mechanically a cut above the DHQ. The DHQ base is laminated particle board that may be more prone to warping, chipping and water damage than the premium plywood. The DHQ focuser is a cheap, imported unit. Some people have had problems with it, such as extra play and roughness in the focus motion. In many cases, these can be alleviated through adjustment, but there's no question that the focuser supplied with the PDHQ is much better. Finally, the standard 6x30 finder supplied with the DHQ scopes is almost universally acknowledged to be JUNK, so DHQ purchasers will want to get a Telrad or reputable magnifying finder (see next section about customization).--Wes Stone

2.6) Can I customize my order?

Some people have.  The Discovery guys have been very accommodating, according to most reports.  People have asked them to delete some of the standard accessories for credit toward optional accessories (the most popular change is to get rid of the standard DHQ eyepieces and finder in exchange for a Telrad, or to exchange a standard eyepiece for one of a different focal length). If you're interested, the credit on the 6x30 finder is $6, as of February 2003. ;) I have also heard of customers asking for the focuser to be put on the left side of the tube, or for the tube to be made a bit shorter. As always, check with the company for details.--Wes Stone

[Rich Dodson] Another feature that Discovery seems very willing to customize is the size of the secondary.  Some people like to keep the secondary diameter down around 15% of the primary diameter for planetary and lunar viewing.  Discovery tends to "oversize" their secondaries (about 20%) which is optimal for deep-sky viewing with an f/5 scope.

2.7) Can I special order a hybrid telescope?

Any requests are handled on a case by case basis based on a variety of factors, including cost, parts availability and a variety of other factors internal to Discovery's operations.  Some have said that if you buy the telescope from Oceanside Photo & Telescope, they're more likely to accommodate special modifications.  But anyone desiring said modifications or unadvertised features is well-advised to consult with Discovery, as well.

DDU member Dirk Thayer went through OPT for a mildly special ordered 8 inch DHQ:

[Dirk Thayer] Although OPT were definitely willing to do the Pyrex mirror upgrade, I ended up getting the DHQ with the standard mirror. Both Discovery and OPT advised against the Pyrex upgrade, saying that in the 8 inch size any improvement with the upgraded mirror would be negligible. I did upgrade the focuser -- but to the 1.25 inch reverse Crayford -- *very* smooth and half the upgrade cost of the 2 inch.

2.8) What's the deal with Discovery telescope lead times?

The bigger the mirror, the longer the wait, in general. PDHQ and truss-tube orders can go from 1 month up to a year.  The year-long lead time orders are rare, but they have happened.

The biggest issue seems to be that Discovery will tell customers that their scope will ship shortly, sometimes giving a definite ship date, without shipping for weeks or months beyond that date. Several customers report being strung out several times, and the general feeling among the group is that Discovery is being a bit dishonest in their promises to customers. Some comments on the mailing list have indicated a recent improvement here. --Wes Stone

It would be folly to state in this static document what "current" lead times are expected to be, but let me take a general stab, based on what I've read.  This is a SWAG, a guesstimate.

This is by far the most hotly discussed topic on the list, because Discovery is, frankly, not very good at predicting their lead times on larger aperture scopes.  The bottleneck in the process appears to be the production of the optics.  They just aren't able to churn out enough samples that are up to their specifications.  Silver lining: That Discovery appears to be standing by their no-compromise stance, in the face of the long lead times and the frustrated customers, says something.  The mantra of the person who is waiting for their scope, often repeated online, is: "It will be worth the wait.  Just a few more weeks.  Just a few more weeks.  It will be worth the wait."

2.9) Where can I read some reviews about Discovery telescopes?

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